Alkali button battery

ABSTRACT

An alkali button battery comprising a highly alkaline electrolyte and wherein a gold or gold alloy coating is formed on at least part of the terminal surface of its positive and/or negative electrodes without being connected with the interior of the battery.

United States Patent wik Q Kasai Sept. 16, 1975 ALKALI BUTTON BATTERY [56] References Cited [75] Inventor: Yoshihiko Kasai, Shimosuwa-machi, UNITED STATES PATENTS Japan 2,829,189 4/1958 Coleman et a1 136/107 [73] Assignee: Kabushiki Kaisha Suwa Seikosha, 5 2 2 3 3 g r i Tokyo, Japan ,673, O0 /1 uetsc 1 O7 [22] Filed: June 1974 Primary Examiner-Anthony Skapars [211 App] 477 0 5 Attorney, Agent, or FirmWaters, Schwartz & Nissen [30] Foreign Application Priority Data ABSTRACT June 7, 1973 Japan 4864080 An alkali button battery comprising a highly alkaline electrolyte and wherein a gold or gold alloy coating is [52] US. Cl. 136/111 formed on at least part of the terminal surface of its [51] Int. Cl. H0111] 21/00 positive and/0r negative electrodes without bein co [58] Field of Search 136/1 11, 107, 134, 135, nected with the interior of the battery,

6 Claims, 4 Drawing Figures ALKALI BUTTON BATTERY BACKGROU ND a.'Field'of'the Invention I t This invention relates tolan alkali button battery in- 2 2 The values of leakage are obtained according to the ten time -lC/24I-l, +60C/24l-l thermal cycle test.

As seen from Table 1, the desired battery characteristic canbe obtained only by providing a gold or gold alloy plating on the outer surface of the battery case. eluding a g y alkaline electrolyte. The plating can be effected by means of plating, depo- Prior A11 sition, cladding,. adherence or the like. Convcntionally, most alkali batteries use nickela l plated steel or stainless steel for their battery case .ma- BR ,Q R T OF THE DRAWINGS terial. Nickel alloys such as monel metal are regarded FIG. 1 isasectional view of a conventional battery as preferable. in which the inside surface of an anode cap of stainlessl-lowever, since their electrical contact resistance is teel is providedw a e e cladding, g a relatively great Contact Pressure is required y .FIG. 2 is asectional view of a battery in which the inthe terminal Spring of an instrument: in which the side surface of a copper clad stainless-steel anode cap tery is used. Thereby, the battery is strongly comi5 is provided with a gold plating on both the inside and pressed and causes long term'leakage at the interface outside surfaces thereof, of its gasket. This tendency is substantial especially in FIG. 3 is a sectional view of a battery according to smaln'sizedbuttoh batteries I the invention in which only. the outer surface of the Furthermore, it has been establishedexperimentally anode Cap i l d i h a ld l d that the internal resistance of the battery is increased F1(} 4 i a l i f a difi ti i hi h the if a gold or gold alloy coating is electrically connected ldi r i formed in a narrow strip over only the with the alkaline electrolyte inside the battery. 'A silver c t t rtio of th anode cap. oxide-zine alkali battery of a diameter of l 1.6 mm and a a height of 5.4 mm which is plated with a layer of gold DETAILED DESCRIPTION of a thickness of about 1 I inside its p has, in Referring to FIG. 1 wherein a conventional alkaline parisen with an uneoated p of stainless steel i button battery is illustrated, therein are seen its compocopper cladding, an internal resistance of 15 9 comnent parts comprising a d a 1, anode 2, separator pared to o n as measured according to 1,000 HZ aher- 3 containing a highly alkaline electrolyte such as potashatihg current method at a room temperature of sium or sodium hydroxide, cathode 4, cell can or casing +24C. The lower the temperature, the more substan- 5 d gasket 6 i t d b t ee the casing 5 and the tial the diffefenCeanode 2 and anode cap 1. The cathode is constituted SUMMARY OF THE INVENTION of silver oxide hence giving rise to the term fsilver battery. The casing and anode cap are of stalnless-steel Ah object of the invention is to produce an alkaline and the anode cap 1 is provided on its inside surface 7 button battery having reduced internal resistance, rewith a copper Cladding 7 The battery h h characduced contact resistance of the terminal surface of the teristics shown i h l li f T bl 1, battery and minimized leakage- FIG. 2 shows the battery of FIG. 1 wherein a plating This invention contemplates an alkali button battery f ld i id d on b h th inte ior and exterior Provided with a Plating of gold or gold alloy y on the surfaces of the cap 2 and respectively denoted at 10 exterior Surface of its Positive and/o1" negative eleo- 40 and 11. This battery has the characteristics as shown in trede whereby the Contact resistance is reduced. and the middle line in Table 1. FIG. 3 is an embodiment of the internal resistance is not raised and leakage is minih invention d shows th battery of FIG. 1 wherein m only the exterior of the cap is coated with the gold layer It is not certain why the internal resistance is' inas Shown at 11, creased y the Presence 0f gold or gold alley inside the In the embodiment of FIG. 3 the gold layer 11 is conbattery, but it seems that gold ions reduce the reaction i d as an 18 K g ld latin of a thickness of at least area. A battery which includes gold ions near its zinc 1 on th t i surface of the stainless-steel cap negative electrode and at its separator shows an ex- 1, The a i made by draw forming the resulting plated traordinarily high internal resistance. When temperai l, Th t t i tan e, leakage and internal ture is lowered, its Voltage dr p gre tly a its Current resistance of the battery of FIG. 3 using the particular supply becomes very low. coated battery cap are shown in Table 1. When assem- This is demonstrated in Table 1 hereafterbled in a timepiece which is tested for prolonged peril The drop in voltage is for the case when momentary ods, the termmal undergoes damage the load is g 55 contrary, a battery using a stalnless-steel cap without Table 1 contact internal resistance drop in leakresistance (1 (alternating D. voltage age kind of battery current method) at l0C load load 24c 0C IOC 100g 300g gold-plated (only the outer 0.82 0.32 6 32 35 03 surface) gold-plated (also the inter- 0.80 0.30 15 300 600 40 0.3 nail surface) stainless steel 9.00 2.0 6 33 88 I30 2.0

3 the gold plating is discolored at its contact portion, and the contact resistance of the portion is substantially increased.

FIG. 4 shows an arrangement wherein the gold plat" ing layer 11a is formed in a narrow strip covering only the contact region of the battery by any suitable pattern deposition method.

The battery is suitable for use in a hearing aid. In this embodiment, it is possible to satisfy the desired quality with the use of a relatively small amount of gold. The temperature characteristic of the hearing aid is good and a shock-resistant power source for the hearing aid can be guaranteed for this embodiment, as well as that of FIG. 3.

A still greater improvement can be obtained if the exterior surfaces of both the cap 1 and the casing are coated with the gold layers.

As known, alkali button batteries for small-sized electrical instruments can be used in may ways, for example, in electronic Wristwatches, hearing aids, photometers of cameras etc. The battery according to the invention has great industrial value by reason of the reduced contact resistance and reduced internal resistance while longterm stability is obtained.

What is claimed is:

1. An alkali button battery comprising an alkaline electrolyte, an anode, a cathode, an anode cap in electrical contact with said anode, a casing in electrical contact with siad cathode, and a layer of gold or gold alloy on at least one of said cap and casing only on the exterior surface thereof.

2 A battery as claimed in claim 1 wherein said layer is in the form of a narrow strip.

3. A battery as'claimed in claim 1 wherein said layer has a thickness of a least 0.1 .1..

4.- A method of reducing the electrical contact resistance of an alkali button battery without increasing electrical resistance, said method comprising applying alayer of gold or gold alloy on only the exterior surface of at least one of the outer contact surfaces of the battery.

5. A method as claimed in claim 4 wherein said layer is applied in the form of a narrow strip on said exterior surface in the region thereof which is to be electrically contacted.

6. A method as claimed in claim 4 wherein said layer is deposited with a thickness of at least 0.1 .1,. 

1. AN ALKALI BUTTON BATTERY COMPRISING AN ALKALINE ELECTROLYTE, AN ANODE, A CATHODE, AN ANODE CAP IN ELECTRICAL CONTACT WITH SAID ANODE, A CASING IN ELECTRICAL CONTACT WITH SAID CATHODE, AND LAYER OF GOLD OR GOLD ALLOY ON AT LEAST ONE OF SAID CAP AND CASING ONLY ON THE EXTERIOR SURFACE THEREOF.
 2. A battery as claimed in claim 1 wherein said layer is in the form of a narrow strip.
 3. A battery as claimed in claim 1 wherein said layer has a thickness of a least 0.1 Mu .
 4. A method of reducing the electrical contact resistance of an alkali button battery without increasing electrical resistance, said method comprising applying a layer of gold or gold alloy on only the exterior surface of at least one of the outer contact surfaces of the battery.
 5. A method as claimed in claim 4 wherein said layer is applied in the form of a narrow strip on said exterior surface in the region thereof which is to be electrically contacted.
 6. A method as claimed in claim 4 wherein said layer is deposited with a thickness of at least 0.1 Mu . 